﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace WebApiMIT3.Utils
{
    // <Author>Rainer Schmitt</Author>
    // <StudentNo>1235656</StudentNo>
    // Copyright (c) 06/04/2015 All Right Reserved
    // <Date>06/04/2015</date>

    /// <summary>
    /// Contains approximate string matching
    /// </summary>
    public static class CompareUtil
    {
        public static bool IsMoreThan5ProcentDifferent(string oldText, string newText)
        {
            bool result = false;
            int textLength = oldText.Length;
            int newTextDifferences = Compute(oldText, newText);

            double procentChars = textLength * 0.05;

            result = (newTextDifferences > procentChars) ? true : false;

            return result;
        }

        /// <summary>
        /// Compute the distance between two strings.
        /// </summary>
        private static int Compute(string s, string t)
        {
            int n = s.Length;
            int m = t.Length;
            int[,] d = new int[n + 1, m + 1];

            // Step 1
            if (n == 0)
            {
                return m;
            }

            if (m == 0)
            {
                return n;
            }

            // Step 2
            for (int i = 0; i <= n; d[i, 0] = i++)
            {
            }

            for (int j = 0; j <= m; d[0, j] = j++)
            {
            }

            // Step 3
            for (int i = 1; i <= n; i++)
            {
                // Step 4
                for (int j = 1; j <= m; j++)
                {
                    // Step 5
                    int cost = (t[j - 1] == s[i - 1]) ? 0 : 1;

                    // Step 6
                    d[i, j] = Math.Min(
                        Math.Min(d[i - 1, j] + 1, d[i, j - 1] + 1),
                        d[i - 1, j - 1] + cost);
                }
            }

            // Step 7
            return d[n, m];
        }
    }
}
